<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div {
            display: flex;
            height: 300px;
            width: 700px;
            background-color: pink;
        }

        div p {
            /* 剩余的份数 */
            flex: 1;
            background-color: aqua;
        }

        div p:nth-child(2) {
            /* 数值越小越靠前 */
            order: -1;
            flex: 2;
            background-color: red;
        }
    </style>
</head>

<body>
    <div>
        <p>1</p>
        <p>2</p>
        <p>3</p>
    </div>
</body>

</html>